The
turquoise color of Lower Grinnell Lake, in the foreground, is caused
by "glacial milk," suspended
calcium carbonate (limestone) in the meltwater runoff of Grinnell and Salamander
Glaciers. The glaciers move slowly downhill and grind their limestone bed
into fine particles, which remain in suspension and flow with the meltwater
in the waterfalls. Lake Josephine, in the distance, is a more typical blue
color because it is fed by other mountain streams as well. This valley, like
others in Glacier National Park, was carved into a
U-shape by the huge contintental glaciers of the Pleistocene epoch.
